In this article, we’ll talk about the different sizes of power banks and how you can determine what size you need.
A power bank is a portable charger that you can use when you don’t have access to an electrical outlet. They can be used as a backup battery for anything that may need charging (phone, laptops, speakers, watches, etc). However, not all power banks are created equal, and finding the right capacity for your needs can be challenging.
When describing a power bank’s capacity, the term mAh (milliampere-hour) is most commonly used. This is a unit of measurement that describes the capacity of a battery, and it is used to indicate how much energy a battery can store. The higher the mAh number, the more charge a power bank can hold. For example, a power bank with a capacity of 10,000 mAh can charge a phone with a 3000 mAh battery 3 times before needing to be recharged itself.
The mAh (milliampere hour) of a power bank is determined by measuring the amount of electrical charge that the power bank can deliver over a certain period of time. Specifically, one mAh is equal to one-thousandth of an ampere-hour, which is the amount of current that a battery can deliver for one hour. For example, if a battery has a capacity of 3000 mAh, it means that it can deliver 3,000 milliamps (3 amps) of current for one hour or 1.5 amps of current for two hours.
The mAh of your power bank does not directly affect the speed at which your devices charge. The speed at which your devices charge is determined by the amount of current that the power bank can deliver, which is measured in amps (A).
Most power banks are rated in terms of their maximum output current, which is the maximum amount of current that they can deliver at any given time. The output current, in conjunction with the mAh capacity, determines how many times your device can be charged and how quickly it can be charged.
For example, if a power bank has an output current of 2A and a capacity of 10,000mAh, it will be able to charge a device with a 3000mAh battery in about 1.5 hours, assuming that the power bank is fully charged.
Technically, there is no maximum mAh capacity for a power bank. Power banks are available in a wide range of capacities, from as little as 1000 mAh to as much as 50,000 mAh or more. However, it’s worth noting that as the mAh capacity of a power bank increases, so does its physical size and weight– which can be a serious detriment in the backcountry or while traveling. Bigger is not always better! A power bank with a higher mAh capacity is also likely to be more expensive than one with a lower capacity.
Think about what you will use your power bank for. Will it be a backup battery for your phone? A power source for a wireless speaker around the campfire, keeping a laptop charged while traveling? You might not actually need the extra mAh that a heavy, expensive ultra-high capacity power bank has to offer depending upon your needs.
Hiking, traveling, or just being anywhere with a dead phone can be anxiety-inducing, especially if you were using it for GPS. It’s important to know your phone’s battery size so that you can pick a power bank that can charge it from zero to full in case of an emergency. Since it’s likely that charging your phone is the most common use of your power bank, this can help you choose what size of power bank to buy.
| Phone Model | Battery Capacity |
| Apple iPhone 13 Pro Max | 4,352 mAh |
| Apple iPhone 11 Pro | 3,190 mAh |
| Apple iPhone X | 2,716 mAh |
| Google Pixel 7 Pro | 5,000 mAh |
| Google Pixel 5a | 4,680 mAh |
| Motorola Edge 30 Fusion | 4,400 mAh |
| Motorola One Fusion+ | 5,000 mAh |
| Moto G Power | 5,000 mAh |
| Samsung Galaxy S20+, S20FE | 4,500 mAh |
| Samsung Galaxy S21 Ultra | 5,000 mAh |
| Samsung Galaxy A21s | 5,000 mAh |
With these numbers in mind, what battery capacity should you be looking for? For best results and to make sure that you always have emergency power, your power bank should be enough to provide around a single round and half of the charge cycles for a phone.
However, it’s not a straightforward equation. You have to consider the conversion ratio. Smartphones have a power rating of 5 volts, but the Li-ion battery cells of power banks carry a rating of 3.7 volts– which causes a step down in the charge cycles.
Fortunately, there’s an easy equation to figure out the size you need.
Let’s say that your power bank has 5,000 mAh. You need to multiply the capacity by the volt rating to get the mWh: the megawatt-hour rating. Then, divide that by the voltage rating of your phone– 5V.
Here are some of the common power bank sizes, their conversions, and the actual capacity when charging your phone. Divide the actual capacity by the mAh of your phone to find out how many times your phone can be charged with a particular power bank size!
| Power Bank Size | Power Bank mWh (mAh x 3.7) | Power Bank Actual Capacity for Phone Charging (mWh/5) |
| 5000 mHa | 18,500 mWh | 3,700 mAh |
| 10000 mHa | 37,000 mWh | 7,400 mAh |
| 20000 mHa | 74,000 mWh | 14,800 mAh |
| 25000 mHa | 92,500 mWh | 18,500 mAh |
| 30000 mHa | 11,1000 mWh | 22,200 mAh |
| 50000 mHa | 185,000 mWh | 37,000 mAh |
Many people use their power banks for their phones, but there are lots of things you can charge up with a power bank. Here are some of the most common things you might want to use your power bank with.
| Device | Minimum mAh needed for one complete charge |
| Phone | 5,000-10,000 |
| Camera | 5,000 (10,000 for more powerful DSLRs) |
| Drone | 5,000 |
| GPS Unit | 5,000 |
| Smartwatch | Most power banks will be able to charge this several times over |
| Tablet | 20,000 |
| Laptop (lightweight, like a Macbook Air or Chromebook) | 30,000 |
| Wireless headphones | Most power banks will be able to charge these several times over |
Power stations are another form of portable power that you may want to use for camping– but there are some key differences between the two, and generally, a power bank and a power station do very different jobs. Power stations are much larger and designed to help run appliances, laptops, or even power tools when you don’t have power; power banks are much smaller and designed to be used for personal electronics.
We have a great guide to power stations if you want to know more about them, but for quick reference here are the key differences between power banks and power stations
| Power Bank | Power Station | |
| Size | Small, portable devices that can fit in a pocket or bag | Large and heavy; not usually designed with portability in mind (and portable ones are still heavier and bulkier than power banks) |
| Capacity | Relatively small, usually ranging from 1,000 mAh to 20,000 mAh | Higher capacity, ranging from 10,000 mAh to over 50,000 mAh |
| Output | Usually one or two USB ports for charging phones, tablets, and other small devices | Typically have multiple outputs, including USB, AC, and DC ports, which can power a wide range of devices, including appliances |
| Durability | Designed to be lightweight and portable, which means they are not always built to withstand rough handling or extreme weather conditions | Often built with durable materials and can withstand harsh environments and emergency situations |
| Recharging | Recharged via a USB cable connected to a computer, wall adapter, or an adapter that fits in your car’s power outlet | Recharged via a solar panel, a car charger, or an AC wall outlet |
When it comes to power banks, Anker is one of the most popular, well-regarded brands. While they aren’t the only good power bank brand, you can’t go wrong with an Anker power bank, so we have a separate guide to Anker’s power banks. But there are other great power bank brands, so we’ve featured a variety of products that might be just what you need.
This slim, compact model can charge most phones from zero to full at least twice and has a 20-watt USB C port that can charge your phone from zero to 50% in about half an hour. It weighs less than a quarter of a pound and is small enough to fit into any pocket or bag.
The iMuto is a little bulky, but its features are pretty great. This power bank has a screen that tells you exactly how much charge is left on the device, and its four output USB ports are clearly labeled to tell you how much power each one can transfer.
The Morphie Powerstation Plus features a built-in USB-C cable and can power two devices at once. When plugged into a power source, its smart power feature kicks in, meaning that it bypasses your bank’s battery storage to fully charge your devices before charging the battery. This feature means that you can easily and safely use it as a wall charger for your devices.
The Powerstation XL’s bigger sibling, this power bank can charge three devices at once and has a soft-touch fabric finish to keep it from scratching any of your surfaces. It’s just like the Morphie Powerstation Plus XL, but bigger.
This tiny power bank carries just enough juice to get your phone all the way charged once or twice– but that might be all you need. This is a perfect power bank for everyday carry, and while you might want something more substantial in the backcountry, this is great for small devices that don’t need frequent full charges.
This itty bitty power bank packs a major power punch– with over 10k mAh, it can charge your phone multiple times and is remarkably compact. At less than 4 inches long and shorter than 3 inches high, and weighing a mere 7 ounces, this power bank is a great fit for an ultralight backpacker or somebody who doesn’t want to be weighed down with a bigger bank.
This beefy bank can charge up to six devices at once, making it almost feel like a lighter power station. It has a massive mAh capacity and is about the size of a book. It is great for times when you need a little more power and can stand to take the extra weight, like a long camping trip.
This power bank also works as a portable charger and has two built-in cords with both a USB-C and a lightning-type connection; perfect if you want to charge your iPhone and something else. It plugs directly into the wall, so you don’t need a separate power cube if you want to plug it in and don’t have USB slots available.
This high capacity option is pretty big, but depending on what you need it for, it might be worth it. Unlike most power banks, this power bank has an AC plug built into it, so you can directly plug in things that pull AC power like a fan, lamp, or other small appliance.
Just like the Energizer bunny, this power bank will keep you going… and going… and going… with its high capacity and rapid charging speeds. It has dual outputs and dual inputs, so you can charge it via USB-C or micro USB, depending on what cord you have handy.
Another unusual power bank that offers an AC outlet, this power bank includes a flashlight and an LCD screen to tell you how much power is left. It’s heavy, durable, and great in case of emergencies. This power bank can charge up to four devices at once.
